LONDON/ZURICH, Nov 16 (Reuters) - European regulators are
expected to adopt a conservative stance this week when they set
rules for allowing copies of antibody drugs, used to fight
cancer, rheumatoid arthritis and other serious diseases.

The new guidelines from the European Medicines Agency (EMA)
will open up a multibillion-dollar market to cheaper rivals, but
the key question is how difficult -- and hence expensive -- it
will be to win approval for so-called biosimilars.

Industry experts expect a cautious approach, requiring
separate clinical trials for different diseases addressed by the
same antibody. That would be good news for original producers of
monoclonal antibodies, like Roche (ROG.VX) and Amgen (AMGN.O).

For makers of generic drugs, it would push up costs and may
limit the field to a few sophisticated and well-funded companies
like Teva TEVA.O, which is working on biosimilars with Lonza
(LONN.VX); Novartis (NOVN.VX) unit Sandoz; and Hospira (HSP.N).

Lincoln Tsang, a partner at London law firm Arnold & Porter
and a former head of biotechnology at Britain's regulatory
authority, expects the EMA to play it safe by requiring
extensive testing.

"My hunch is that they will be cautious in saying that if
you can establish clinical efficacy and safety of a given
product for a given indication you can't readily seek approval
for another indication," he said.

"Given it is such a big therapeutic area, I think they will
not like to be seen to be too generous."

Drawing up rules for copies of biotech drugs like antibodies
is tricky because they are complex molecules grown in living
cells that cannot be made absolutely identical to the original.

The agency's Committee for Medicinal Products for Human Use
(CHMP) will decide this week whether to adopt the new
guidelines, although it may be another two or three weeks before
they are actually published, an EMA spokeswoman said.

There will then be several months of external consultation
before the guidelines are formally adopted. [ID:nLDE6901QO]

ROCHE DRUG IS TEST CASE

The first antibody likely to be copied in Europe is Roche's
Rituxan, or MabThera, which loses patent protection in 2014.

Teva is already running separate clinical trials for its
biosimilar version in the drug's two main uses -- non-Hodgkin's
lymphoma and rheumatoid arthritis -- showing it is not banking
on simple extrapolation of approval from one disease to another.
[ID:nLDE68L1CW]

"Teva has started clinical trials for each indication. They
are cautious. They are conservative," said Lonza spokesman
Dominik Werner.

"At the moment we expect that a Phase I (trial) will be
required and also a Phase III. The key question is whether a
Phase II is also needed. We expect (R&D) costs of $100 million
per antibody. If a Phase II is also be needed, we are talking
about an additional $20 million, depending on the antibody."

Up to now, complex biotech medicines have been generally
immune from generic competition, unlike conventional pills and
capsules. That is starting to change as patents expire and
regulators work on ways to allow safe and effective copies.

Europe has so far approved 13 biosimilars and the EMA
already has six sets of guidelines on simpler biosimilar drugs,
including human growth hormone and anaemia treatment EPO.

Monoclonal antibodies, however, are the biggest commercial
prize, since these treatments are expected to dominate many
areas of medicine in the years ahead.

Worldwide sales of all biologic drugs reached some $130
billion in 2009, according IMS Health, and industry analysts
believe the potential market for biosimilars could be worth tens
of billion of dollars by the second half of the decade.
(Editing by David Cowell)